Direct electrochemistry of hemoglobin adsorbed on self-assembled monolayers with different head groups or chain length.

Abstract

The electrochemical behaviors of hemoglobin (Hb) were studied by adsorbing Hb on the gold electrodes modified with self-assembled monolayers (SAMs) of different terminal groups and alkyl chain length. Specifically, through adsorbing the Hb molecules onto the SAMs of 3-mercaptopropanoic acid (MPA), 1-propanethiol (PT) and cysteamine hydrochloride (cys), the influences of the terminal groups of alkanethiols on the electron transfer of Hb were examined. A quasi-reversible redox process was observed when Hb was adsorbed on the MPA-modified electrode. However, an irreversible reduction process and no redox response were shown when Hb molecules were adsorbed on the SAMs of PT and cys-modified electrodes, respectively. The dependence of the direct electrochemical response of Hb on the alkyl chain length of alkanethiols (n) was further investigated on the SAMs of HS(CH(2))(n)COOH (n=1, 2, 5 and 10). When n was 1, Hb showed a weak current response. When n were 2 and 5, quasi-reversible redox processes with nearly similar electron transfer rate constants (k(s)) of 0.49 and 0.47 s(-1) were obtained, respectively. Increasing the number of methylene groups within carboxyl alkanethiol to 10 resulted in a significant decrease of the electron transfer rate and current response of Hb. The observations indicated that the SAM of MPA can provide suitable properties to keep Hb in a favorable adsorption state for direct electron transfer (DET). Furthermore, the direct electrochemistry of the Hb adsorbed on the SAM of MPA was studied in detail.

• Authors: Zhibin Mai, Xiaojuan Zhao, Zong Dai, Xiaoyong Zou
• Journal: Talanta (Talanta) Vol. 81 Issue 1-2 Pg. 167-75 (Apr 15 2010) ISSN: 1873-3573 [Electronic] Netherlands
• PMID: 20188904 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
• Copyright: (c) 2009 Elsevier B.V. All rights reserved.

Chemical References

• Hemoglobins
• Sulfhydryl Compounds
• Gold
• 3-Mercaptopropionic Acid
• Hydrogen Peroxide

Topics

• 3-Mercaptopropionic Acid (chemistry)
• Adsorption
• Animals
• Catalysis
• Cattle
• Electrochemistry
• Electrodes
• Electron Transport
• Gold (chemistry)
• Hemoglobins (chemistry)
• Hydrogen Peroxide (chemistry)
• Hydrogen-Ion Concentration
• Sulfhydryl Compounds (chemistry)
• Surface Properties